1. Field of the Invention
The present invention relates to a system of electronic reprographics and, more particularly, to a system of electronic reprographics in which productivity is improved when printer job recovery is required.
2. Description of the Related Art
In light lens printing systems, a lamp or flashing unit flashes light on a document and has an image created synchronously on a photoreceptor belt. The photoreceptor belt picks up toner from which a copy is made.
In electronic reprographic printing systems, a document or series of documents comprising at least one print job are successively scanned. Upon scanning of the documents, image signals are obtained and electronically stored. The signals are then read out successively and transferred to a printer for formation of the images on paper. Once a document is scanned, it can be printed any number of times or processed in any number of ways (e.g., words deleted or added, image magnified or reduced, etc.). If a plurality of documents comprise a job which is scanned, the processing or manipulation of the scanned documents can include deletion of one or more documents, reordering of the documents into a desired order, or addition of a previously or subsequently scanned document or documents. The printing or processing can be relatively synchronous with scanning, or asynchronous after scanning. If asynchronous, a time interval exists between scanning and printing or processing. The system can then accumulate a number of scanned jobs in the system memory for subsequent processing or printing. The order of the jobs to be printed may be different from the order of jobs as scanned depending on the priority of the jobs and the desires of the operator for increasing productivity or through-put and decreasing printer or scanner down-time.
For a variety of reasons, operation in an electronic reprographic system can be interrupted. This can be the result of a scanner or printer fault, hardware or software faults, paper misfeed, intentional interruption, memory loss, etc. Upon such an interruption resulting in failure to complete printing of all the jobs in the system, the system commonly may either remake all the jobs or remake all the partially complete jobs except the oldest partially complete job to ensure that all jobs are complete. The oldest partially complete job is the partially complete job which started printing before all other partially complete jobs. This significantly reduces the productivity of the system, increases sheet waste and provides redundant job output.
The related art has disclosed printing systems which provide job recovery when a system fault occurs.
U.S. Pat. No. 4,229,100 to Travis discloses an automatic copy recovery system wherein a jam of a copy set is detected and the copy set is recovered using three counters to keep track of the copy set. Each counter contains a number of copies which have passed a sensor attached to the counter. A method of correctly billing a user when a jam occurs is shown. A method of recovering from three separate job recovery situations is shown.
U.S. Pat. No. 4,521,847 to Ziehm et al discloses a control system for job recovery after a malfunction occurs wherein a method of job recovery of a second job during a job interrupt is shown. During the interrupt condition, the first interrupted jobs variables are stored in memory. When a fatal software fault occurs within copier, the current job's necessary parameters are stored in a memory until such time as the problem is fixed.
U.S. Pat. No. 4,327,993 to Gauronski et al discloses a method and apparatus for performing job recovery in a reproduction machine wherein a number of job recovery schemes are shown for various types of jobs. No mention is made of multiple partially complete job recovery.
While the related art recognizes that job recovery can be provided in a printing system, it does not recognize the problems associated with job recovery in a system where some jobs may be complete or partially complete before fault occurrence.